I have just put a split exhaust in my '49 Coronet. I had a local welder put in the second outlet but most are just like what George does. You will have to pull the intake and exhaust manifolds to get this done. Take your time. Get a service manual if you can. I would go with the original size on the exhaust. I ran my duals together and they both come out on the passenger side. I have seen others do what your talking about even adding y's to side pipes. Muffler shops can do a lot of things that you wouldn't think possible. Go ahead and put in some sort of mufflers. I run a couple of short glasspacks and I'm satisfied. Straight pipes will sound cool the first couple of days but you will become annoyed with them. You might try visiting these guys they have a lot of experience and tech advice for these old mopars.
http://www430.pair.com/p15d24/mopar_forum/forumdisplay.php?f=2
